How Ag Nanospheres Are Transformed into AgAu Nanocages

Liane M. Moreau, Charles A. Schurman, Sumit Kewalramani, Mohammad M. Shahjamali, Chad A. Mirkin*, Michael J. Bedzyk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Bimetallic hollow, porous noble metal nanoparticles are of broad interest for biomedical, optical and catalytic applications. The most straightforward method for preparing such structures involves the reaction between HAuCl4 and well-formed Ag particles, typically spheres, cubes, or triangular prisms, yet the mechanism underlying their formation is poorly understood at the atomic scale. By combining in situ nanoscopic and atomic-scale characterization techniques (XAFS, SAXS, XRF, and electron microscopy) to follow the process, we elucidate a plausible reaction pathway for the conversion of citrate-capped Ag nanospheres to AgAu nanocages; importantly, the hollowing event cannot be explained by the nanoscale Kirkendall effect, nor by Galvanic exchange alone, two processes that have been previously proposed. We propose a modification of the bulk Galvanic exchange process that takes into account considerations that can only occur with nanoscale particles. This nanoscale Galvanic exchange process explains the novel morphological and chemical changes associated with the typically observed hollowing process.

Original languageEnglish (US)
Pages (from-to)12291-12298
Number of pages8
JournalJournal of the American Chemical Society
Volume139
Issue number35
DOIs
StatePublished - Sep 6 2017

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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